1. Field of the Invention
The present invention relates to electrical connectors. More specifically, the present invention relates to pogo pin-type coaxial and twinaxial connectors.
2. Description of the Related Art
One known connector used with automatic testing equipment includes a sub-connector that has pogo pins soldered to both sides of a circuit board. Sub-connectors are arranged into an array to form the connector. Pogo pins include a socket, a pin that is partially disposed in the socket, and a spring disposed in the socket that pushes the pin away from the socket. This arrangement allows the pogo pins to travel within the socket.
Conventional pogo pins suffer from several drawbacks. First, the pogo pins are relatively long. Because pogo pins are relatively long, it is difficult to design a compact connector. Also, the length of the pogo pins often causes significant portions of the pogo pins to be unshielded, which results in impedance discontinuities, attenuation, and low signal integrity. Second, pogo pins are expensive because of the difficulties in their manufacturing and tight tolerances for many of the components of the pogo pins. Third, the total downward force required to engage all of the pogo pins with the mating circuit board is quite large due to variances in the dimensions of the pogo pins, particularly the exposed length of the pogo pin which requires the spring to have a high spring constant. Fourth, it is difficult to ensure proper impedance matching of the connectors due to unshielded portions of the pogo pins and variances in the dimensions of the pogo pins. Fifth, conventional pogo pins are often connected to cables by receptacles, rather than solder, which further increases the difficulties in providing consistent impedances among electrical connectors.
FIGS. 19 and 20 show a conventional pogo pin connector 110 disclosed in U.S. Pat. No. 6,261,130. As shown in FIG. 19, pogo pins 114a, 114b, and 114c of the pogo pin connector 110 have significantly different lengths, which increases the mating force required to ensure that all of the pogo pins 114 are mated with their corresponding contact regions 118. For example, a spring of the pogo pin 114b is compressed further than a spring of the pogo pin 114c when the pogo pings 114 are mated with their corresponding contact regions 114. Further, as shown in FIG. 20, a significant portion of each of the pogo pins 114 is exposed when the pogo pins 114 are mated with their corresponding contact regions 118, resulting in impedance discontinuities, attenuation, and low signal integrity.
FIG. 21 shows a conventional pogo pin contact 120 disclosed in U.S. Pat. No. 8,337,256. As shown in FIG. 21, the pogo pins 121 of the pogo pin contact 120 include springs 122 that provide a compressive force to mechanically mate the pogo pins 121 with corresponding contact regions of a circuit board or contact section of a connector. However, because the pogo pin contact 120 relies on the force of the springs 122, the pogo pins 121 are subject to swaying or misalignment due to the lack of any guide or support elements near the tips of the pogo pins 121. Further, a significant portion of each of the pogo pins 121 is exposed, resulting in impedance discontinuities, attenuation, and low signal integrity.
Thus, known connectors that include pogo pins typically have impedance discontinuities, attenuation, and low signal integrity in the termination region, that is, in the area where pogo pins are connected to a circuit board or other electrical components within the transceiver. More specifically, since pogo pins provide an exposed portion of the conductor along which a signal is transmitted, shielding elements of the connectors do not cover the entire length of the signal transmission distance. The exposed (unshielded) portions of the pogo pins allows the pogo pins to receive excessive external noise and crosstalk from neighboring pogo pins, as well as impedance discontinuities, attenuation, and low signal integrity.
FIG. 22 is a side view of a conventional pogo pin connector 130 with a spring-loaded shield 135. As shown in FIG. 22, one known method to reduce the negative effects of the unshielded portions of the conventional pogo pin 132 of the pogo pin connector 130 is to include the spring-loaded shield 135, which surrounds the pogo pin 132 and compresses along with the pogo pin 132 during mating. However, although this arrangement reduces the unshielded portion of the pogo pin 132, the spring-loaded shield 135 typically only provides a marginal improvement in signal integrity over simply allowing the unshielded portion of the pogo pin 132 to remain exposed. Further, the spring-loaded shield 135 increases the complexity and cost of the pogo pin connector 130 and introduces structurally weak connections into the pogo pin connector 130, particularly between the pogo pin 132 and the signal conductor 133 and between the spring-loaded shield 135 and the shield sheath 136. The spring-loaded shield 135 also typically has a relatively large diameter that reduces the density of the pogo pin connector 130 and requires a dielectric insulator 137 be included between the signal conductor 133 and the shield sheath 136.
Conventional pogo pin connectors have also included springs that are externally located to provide a compressive force to mechanically mate the pogo pin connectors with a connector body, circuit board, or the like. However, these external springs are typically formed of metal, and thus introduce capacitances and inductances that negatively affect the signal integrity of signals passing through the pogo pin connectors, even if the external springs are specially cut or formed to connect to ground or a shield conductor. External springs also reduce the density of pogo pin connectors.